Machine for stacking nestable extruded cans

Abstract

A can stacking infeed machine for stacking nestable extruded cans where can diameter is greater than can height, includes a pair of gravity chutes for dividing an elevated stream of cans at input into two streams of cans, one above the other at output. A rotating starwheel collocates the cans sliding down the chutes one above the other for discharge in vertically registering pairs. A leaf spring mechanism urges the bottom of the upper can into nested engagement with the top of the lower can as the starwheel rotates releasing the cans to slide from the machine. Normally open switches located for sensing the flow of cans down both gravity chutes interrupt rotation of the starwheel thus preventing discharge of a single can from either chute. Stacked can pairs are accelerated upon release by the rotating starwheel as they slide from the machine to provide spacing.

What is claimed is: 
     
       1. A machine for stacking nestable containers comprising in combination, a pair of inclined chutes each having a sliding platform, two side rails, and a top rail which, in combination, define two horizontally parallel channels at an elevated level each shaped to receive one container at a time, the channels becoming vertically parallel, upper and lower chutes at a lower elevation, the chutes bridging from the elevated level at their upper ends to a lower level at their lower ends, whereby a stream of the containers at the elevated level is received and divided into two single file container streams which are positioned vertically parallel one above the other at a lower elevation as the containers slide down the chutes from the elevated level toward the lower level;   collocating means located proximate the lower ends of the chutes for positioning the containers sliding down the chutes in vertically registering pairs, and discharging each vertically registering pair of containers from the chutes to the lower level, the sliding platform of the upper chute having a lower end with a concave scalloped configuration at a point less than one container diameter upstream from the collocating means;   resilient means for urging each vertically registering pair of containers into nested engagement as each container sliding down the upper chute slides off the concave scalloped lower end of the sliding platform of the upper chute;   accelerating means receiving each pair of vertically nested containers as the containers are discharged from the chutes accelerating and conveying each pair of nested containers onto the lower level for establishing spacing between the vertically nested containers on the lower level, whereby, a stream of single containers received at the elevated level are stacked and spaced apart in nested pairs at the lower level.   
     
     
       2. The machine of claim 1 wherein the collocating means includes: a shaft journaled for rotation about an axis perpendicularly oriented with respect to the two vertically related single file container streams sliding down the pair of chutes;   a starwheel journaled to the shaft having a plurality of arms symmetrically extending from its hub for simultaneously intercepting a container in each chute as the containers slide single file down the chutes, each extending arm of the starwheel revolving into the respective single file container streams as the shaft rotates establishing vertical registry of the respective cans in the respective container streams intercepted;   normally engaged brake means for braking rotation of the shaft;   motor means for rotating the shaft; and   a control means switchable between an on condition an an off condition for simultaneously releasing the normally engaged brake means and energizing the motor means for rotating the shaft upon being switched to the on condition and for simultaneously de-energizing the motor means and allowing the normally engaged brake means to engage braking rotation of the shaft upon being switched to the off condition.   
     
     
       3. The machine of claim 2 further including normally open sensing means, sensing presence and absence of containers sliding down each chute coupled to the control means for switching it to an off condition interrupting discharge of containers from both chutes responsive to an absence of cans sliding down one of the chutes and switching it to an on condition responsive to container sliding down both chutes. 
     
     
       4. The machine of claim 3 wherein the normally open sensing means is located upstream from the starwheel. 
     
     
       5. The machine of claim 4 wherein the normally open sensing means comprises a limit switch mounted on the top rail of each chute, each limit switch having an arm pivotable between a closed position resting on a top of a container sliding down the particular chute and an open position resting on the sliding platform of the particular chute for switching the control means to the on and off conditions respectively, the arm extending downward into and in the direction of the particular single file stream of containers sliding down the particular chute, whereby a container must be present in both the chutes supporting the respective pivoting arms of the limit switches for discharge of vertically registering containers from the chutes by the starwheel. 
     
     
       6. The machine of claim 1 wherein the upper chute top rail has a lower end located less than one container diameter beyond the lower end of the upper chute sliding platform; and wherein the resilient means is mounted on the lower end of the upper chute top rail and is positioned for tipping the container sliding off the lower scalloped end of the upper chute sliding platform into nested engagement with the vertically registering container sliding below it in the lower chute.   
     
     
       7. The machine of claim 6 wherein the resilient means comprises a leaf spring element having one end secured to the lower end of the upper chute top rail extending at an angle downwardly approximately one container diameter toward the lower level, its distal end being spaced less than two container heights from the lower chute sliding platform. 
     
     
       8. The machine of claim 2 or 7 wherein the accelerating means comprises an inclined accelerating chute located for receiving each pair of the nested containers as they are released by the extending arm of the starwheel. 
     
     
       9. The machine of claim 8 wherein the accelerating chute has a sliding platform coextensive with the lower chute sliding platform, side rails coextensive with the side rails of both the upper and lower chutes and a top rail which, in combination, define a channel dimensioned for receiving a pair of vertically stacked containers, the accelerating chute curving the stream of vertically stacked containers from a direction inclined downwardly to a horizontal direction, the vertically stacked containers being received by a lower level conveyer.